fixes for building the debian-package
Various fixes to make it possible to build the release-notes as a package, including via
- gbp buildpackage # full build, including pdf (except el, zh_* which do not work - this MR marks them as failing in the Makefile)
- gbp buildpackage --profiles=pkg.release-notes.nopdf # html and text only
- gbp buildpackage --profiles=pkg.release-notes.nopdf,pkg.release-notes.en # html(+text) only en
Closes: #1106574 -- see the last message to that bug